barrett



(No Model.) 4 I 2Sheets-Sheet 1Q J. BARRETT. LIFTING JACK.

No. 312,316. Patented P Y & a A (if 7017? ATTORNEY;

WITNESS S- W2 v 2 Sheets-Sheet' 21 J. BARRETT.

(No Model.)

LIFTING 110K.

WITNEEUSEQSW INVLE%R, QM 1.. w i g I BYMt ATTORNEY NITED STATES PATENTEErcE.

JOSIAH BARRETT, OF ALLEGHENY, PENNSYLVANIA, ASSIGNOR TO THE DUFFllIANUFAOTUR-ING COMPANY, '(LIMITED,) OF SAME PLACE.

LlFTlNG-JACK.-

SPECIFICATION forming part of Letters Patent No. 312,316, dated February17, 1885.

Application filed January 2, 1885. (No model.)

To all whom it n-taty concern, .1

Be it known that I, JOSIAH BARRETT, a citizen of the United States,residing at Allegheny, in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements inLifting-Jacks, of which the following is a specification, referencebeing had therein to the accompanying drawings.

Figure 1 is a View in side elevation of my improved lifting-jack, thecap-plate being removed to show the operation of the pawls and theirconnections. Figs. 2 and 3 are diagrammatic views showing the positionand operation of the pawlsinlowering the lifting-bar. Fig. 4 is a detailview of one of the pawls on an enlarged scale. Fig. 5 shows amodifiedform of the tripping-plate. Figs. 6 and 7 are detail views of thetripping-plate and its operzo ating-eocentric. Fig. 8is atransversesection on the line :0 01;, Fig. 1. Figs. 9and 10 are detail views ofthe end of the operatinglever and one of its side plates. Fig. 11 is anenlarged View of the pivot-pin of the operating-lever.

My invention relates to an improvement in lifting-j acks, the object ofsaid invention being to provide for a continuous movement of thelifting-bar, said movement either up or down being effected equally byboth the upstroke 0 and downstroke of the operating-lever; and to thisend my invention consists, in general terms, in the construction andcombination of parts, all as more fully hereinafter described and.claimed.

The frame or stand 1 is formed'with alongitudinal rectangularly-shapedpassage, 2, (see Fig. 8,) said passage being open on one edge for abouttwo-thirds of the length of the stand. Within this passage is placed thelifting-bar o 3, provided at its lower endrwith a foot, 4., projectingthrough the opening in the side of the stand.

Along one edge of the stand 1 is formed the flange 5, which is providednear its lower 5 end with an abutment, 6, said abutment and flangeforming a socket for the reception of the inner end of the operativelever 7. The inner end consists of a stem or shank, 8, curved on itsunder side, the upper side being shaped as shown in Fig. 9, the groovesa forming seats for the reception of the end of the pawls and the sideplates, 9. (See Fig. 10.) These'side plates are provided at their rearend with a tongue or nib, 10, adapted to fitin a notch, 11, in thelever, and are secured to the sides of the stem by rivets passingthrough the holes 12 in the stem and side plates. In the center of eachof the side plates is formed the hole 13, through which is passed thepivotpin 14, the ends of said pin restingin suitable 6o openings in theabutment 6 and flange 5, the end of the lever, with the side plates,being inserted in the socket between said flange and abutment. Thispivot-pin is held in place by a nib, 15, formed on the pin, said nib,when the pin is inserted, passing through a groove, 16, in the wall ofthe opening in the abutment 6, and entering into a notch, 17, in one ofthe side plates, said groove and notch being in line with each otheronly when the lever is at the lower limit of its movement.

9n each side of the central opening, 13, in each of the side plates areformed the openings or holes 18 and 19, the opening 18 being, when thelever is at the lower limit of its stroke, a little above a horizontalplane pass ing through the center of the pivot-pin 14, and the opening19 being a little to the left of a vertical plane passing through saidpin when the lever is in the position abovestated. In these openings 18and 19 are placed the ends of pivotal shafts 20 and 21, formed on thelower ends of the long and short pawls 22 and 23, said ends beinginserted before the plates are riveted to the stem 8. These pawls areconstructed and arranged to engage one above the other with the teeth24, formed along one edge of the lifting-bar 3.

To form the seats a for the shafts 20 and 21, the stem 8 is cast orotherwise formed in the shape shown by full and dotted lines in Fig. 9.The side plates are secured in place in any suitable manner. Holes arethen drilled through the ribs 1) and the body of the stem in line withthe holes in the side plates and of a corresponding size. The sideplates are then removed, and the top portion of the ribs 1), (shown indotted lines,) surroundingthe holes, is milled away, leaving the stem asshown in full lines in Fig. 9. The seats thus formed will correspondexactly in size and location with the holes 18 and 19 in the sideplates, thus providing a long and durable bearing for the ends of thepawls. The upper edges of the seats a will form stops to limit themovement of the pawls. These pawls are held in engagement with the teethof the bar by spring-levers and 26, pivotally attached to the pawls ashort distance above the trunnions by the screws 27.

Around the pivotal screws or bosses projected from the inner sides ofthe levers are placed the coiled springs 28, one end of each of saidsprings being inserted in lugs 29 on the inner sides of the levers, andthe opposite ends engaginglugs 30 on the pawls 22 and 23. The upper endof the lever 25 is held against an abutment, 31, on the flange 5, andthe projection 32, near the upper end of the lever 26, is held againstthe lever 25 by the springs 28; hence, as the upper ends of these leversare held stationary, as above stated, the tension of the springs causesthe pawls, to which the levers are pivoted, to bear against the toothedbar. In moving the operating-lever up, the outer pawl, 22,will engageone of the teeth of the lifting-bar and cause the same to move up.During the same movement the inner pawl is caused to move down adistance equal to half a tooth, the bar being at the same time raised acorresponding distance by the pawl 22, and during the downward movementof the lever 7 the inner pawl will engage the teeth of the lifting-bar,and cause a further upward movement thereof, and the outer pawl will bemoved down half a tooth to engage another tooth of the bar. To lower theliftingbar, the operation of these pawls is reversedi. e., the outerpawl is in engagement with the lifting-bar during the downward movementof the lever, and the inner pawl is in engagement during the upwardstroke-and to effect this reversal it is necessary that the outer pawlshould be held away from the teeth during the upstroke and the innerpawl during the downstroke. This reversal of normal operation iseflected by the tripping-plate 33, said plate being provided with lugs34 and 35, having suitably-shaped cam-surfaces, adapted for engagementwith the rounded lower ends of the levers 25 and 26. This plate ispivoted at its lower right-hand corner to the abutment 6, (see Fig. 1,)and the lower left-hand corner is supported by an eccentric, 36, fittingwithin a notch in said plate, said eccentric being mounted on a pin, 37,screwing into the stand 1. In the normal position of the eccentric (seeFig. 1) the plate 33 is held in such a position that the lugs 34 and 35are at one side of the path of movement of the ends of the levers 25 and23 during the up and down movements of the operating-lever; but when itis desired to lower the lifting-bar the eccentric 36 is turned, by meansof the wings formed thereon, so as to move the plate upward and to theright, there-. by bringing the lugs 34 and 35 into the path of thelevers 25 and 26. (See Figs. 2 and 3.) In Fig. 2 the lever 7 is at thelower limit of its movement, the lower end of the lever 25 is inengagement with the lug 34, thereby. pushing said end outward, and withit the outer pawl, 22, and the inner pawl is in engagement with theliftingbar'. Now, as the lever 7 is raised, the inner pawl beinglowered, thereby lowering the bar 3, the lower end of the lever 26strikes against the lug 35 and is forced outward thereby, and effects acorresponding inward movement of the upper end of said lever,thuscausingaconsiderabletensiontothe spring 28, the tendency of saidtension being to force the lever and pawl outward. During this downwardmovement of the inner pawl the outer pawl, 22, is moving up, being heldfrom engagement with the lifting-bar by the lug 34, against which thelower end of the lever 25 bears. The pawl 22 is held in this positionuntil the lever 7 is near the upper limit of its stroke, when the lever25 escapes from the lug 34, and the pawl is thrown into engagement withthe bar 3. The further downward movement of the bar is arrested by thisengagement with the outer pawl, and by the continuance of the motion ofthe lever to the end of its stroke the lower pawl is released from theweight of the lifting-bar by the lifting action of the outer pawl, andis free to move outward under the action of the spring 28. The innerpawl having been released, asabove stated, the operative lever is moveddown, thus permitting ofa similar movement to the bar 3, and during thisdownward movement the lower end of the lever 25 engages the lug 34,causing a compression of the spring on said lever similar to that abovedescribed, and the lever 26 moves up along the lug 35 until near the endof the downward stroke, when thelever escapes from the lug, and the pawl23 in turn engages the bar 3, and the pawl 22 is pulled away therefromby its spring, which has been compressed by the engagement of the leverand lug, as above stated. Thus it will be seen that the springs 28 andlevers 25 and 26 act when the lifting-bar is to be raised to force thepawls inward against said bar, and when the bar is lowered the springsand levers act to force the pawls outward, said contrary effects beingproduced by the press ure exerted at the opposite ends of the levers bythe abutment 31 in the first instance acting in one direction, and bythe lugs 34 and 35 in the other instance acting in the oppositedirection.

In lieu of the pivotal tripping-plate 33 a sliding plate (see Fig. 5)may be used, said plate being provided with cam-lugs, and being mountedin suitable ways formed in a plate, 38, corresponding in size and shapeto the flange 5, and forming a cover to the operative parts on the sideof the stand opposite the flange, and being secured thereto by screws.

On the plate 38 is mounted an eccentric fitting in a notch in thesliding plate, and adapt ed to give a back-and-forth movement to theplate, as clearly shown in Fig. 5. The operation and function of thissliding plate are similar to that of the pivotal plate before described.

I claim herein as my invention 1. In a lifting-jack, a toothedlifting-bar, in combination with a pivotal lever, two pawls pivoted tosaid lever, one on each side of its fulcrum-pin, and spring-actuatedlevers pivoted to said pawls, and having their upper ends rigidlysupported as against the action of their actuating-springs,substantially as set forth.

2. In a lifting-jack, a toothed lifting-bar, in combination with apivoted operating-lever, pawls 22 and 23, spring-actuated levers 25 and26,.pivoted to said pawls, and a stationary abutment, 31, adapted tosupport the upper ends of the levers as against the action of theiractuating-springs, substantially as set forth.

3. In alifting-jaok, a lever having-its in-' ner end composed of a stemprovided with curved seats, and of side plates having openings inlinewith such seats, in combination with pawls 22 and 23, having theirpivotal shafts formed integral with their lower ends, said shafts beingconstructed to fit in the openings in the side plates and in the seatsin the stem and have a firm bearing therein, substantially as set forth.

4. In a liftingjack, a toothed lifting-bar, in combination with apivotal lever, two pawls pivoted to said lever, one on each side offulcrum-pin, spring-actuated levers pivoted to said pawls, and havingtheir lower ends rounded, as described, and a movable trippingplatehaving cam-lugs thereon, said lugs being adapted, in certain positionsof the plate, to engage and shift the lower ends of the levers,substantialiy as set forth.

5. In a lifting-jack, a toothed lifting-bar, in combination with apivotal lever, two pawls pivoted to said lever, one on each side of itsfulcrum-pin, spring-actuated levers pivoted to said pawls, and atripping-plate movable to and from the path of the lower ends of thespring-actuated levers, and adapted, in certain positions, to engage andshift said lower ends for the purpose of disengaging the pawls from thetooth-bar, substantially as set forth.

6. In a lifting-jack, a toothedlifting-bar, in combination with apivotal lever, two pawls pivoted to said lever, one on each side of itspivotal point, spring-actuated levers pivoted to said pawls, atripping-plate adapted to engage and shift the levers for the purpose ofdisengaging the pawls from the toothed bar, and an eccentric for movingsaid plate to and from the path of said spring-levers, substantially asset forth.

7. In a lifting-jack, a toothed lifting-bar, in combination with apivoted operating-lever, two pawls pivoted to said lever, one on eachside of its i'ulcrunrpin, and spring-actuated levers pivoted to saidpawls, said levers being so arranged, as described, that when rigidlysupported at their upper ends as against the action of their springsthey will operate to hold the pawls against the lifting-bar, and whensimilarly supported at their lower ends they will cause the pawls tomove away for the lifting-bar, substantially as setforth.

In testimony whereof I have hereunto set my hand.

"Jos ua BARRETT.

Witnesses:

DARWIN S. Worootr'r, R. H. WnITTLnsEY.

